Peripheral Circulation Flashcards
Regarding the permability of capillary vascular endothelium (true or false):
The permeability of a capillary is greatest at the arterial end
False. Along the length of an individual capillary, permeability is greatest at the venous end of the capillary
Regarding the permability of capillary vascular endothelium (true or false):
The permeability of brain capillaries is low
True
Regarding the permability of capillary vascular endothelium (true or false):
The permeability of liver capillary beds is high
True
Regarding the permability of capillary vascular endothelium (true or false):
The permeability of the capillary endothelium is uniform
The permeablility of the capillary endothelium is not uniform, for example:
In body tissues, the permeability of liver capillary beds is high, whereas that of the brain is low (hence the term ‘blood brain barrier’)
The following factor may contribute to systolic aortic murmurs in pregnancy (true or false):
Aortic valve pathology causing turbulent flow
True. Many patients may have their hearts auscultated for the first time in pregnancy. Aortic pathology may first come to light now.
The following factor may contribute to systolic aortic murmurs in pregnancy (true or false):
Decreased haematocrit (reduced blood viscosity)
True. Reynolds number increases as viscosity decreases. Therefore, high velocities and low blood viscosity (as occurs in pregnancy, due to reduced haematocrit) are more likely to cause turbulence.
The following factor may contribute to systolic aortic murmurs in pregnancy (true or false):
Increased flow
True. Reynolds number increases as velocity increases. Therefore, high velocities and low blood viscosity (as occurs in pregnancy, due to reduced haematocrit) are more likely to cause turbulence.
The following factor may contribute to systolic aortic murmurs in pregnancy (true or false):
Increased blood volume
True. High velocities and low blood viscosity (as occurs in pregnancy) are more likely to cause turbulence as the Reynolds number rises.
The following factor may contribute to systolic aortic murmurs in pregnancy (true or false):
Decreased aortic resistance
False. While an increased diameter without a change in flow causes an increase in turbulence, the aorta does not change diameter in pregnancy.
The following attribute is a features of autoregulation (true or false):
Low neurogenic control of the supplying arteriole’s smooth muscle
True
The following attribute is a features of autoregulation (true or false):
Nearly constant blood flow over a wide range of mean blood pressure
True
The following attribute is a features of autoregulation (true or false):
Most evident in skeletal, cardiac and cerebral circulations
True
The following attribute is a features of autoregulation (true or false):
High degree of local control of vascular resistance
True
The following attribute is a features of autoregulation (true or false):
Local changes in tissue metabolic requirements have little influence on flow
False
Match the following value to the relevant pressure type:
35mmHg
A. Arteriolar hydrostatic pressure
B. Venular hydrostatic pressure
C. Oncotic pressure
D. Interstitial osmotic pressure
A.
Match the following value to the relevant pressure type:
25mmHg
A. Arteriolar hydrostatic pressure
B. Venular hydrostatic pressure
C. Oncotic pressure
D. Interstitial osmotic pressure
C.
Match the following value to the relevant pressure type:
15mmHg
A. Arteriolar hydrostatic pressure
B. Venular hydrostatic pressure
C. Oncotic pressure
D. Interstitial osmotic pressure
B.
Match the following value to the relevant pressure type:
5mmHg
A. Arteriolar hydrostatic pressure
B. Venular hydrostatic pressure
C. Oncotic pressure
D. Interstitial osmotic pressure
D.
Match the following function of a vessel with its category:
Contain >60% of the blood volume
A. Arterioles
B. Venule
C. Large arteries
D. Aorta
E. Capillaries
F. Vein
F.
Match the following function of a vessel with its category:
Determines the hydrostatic pressure of capillaries
A. Arterioles
B. Venule
C. Large arteries
D. Aorta
E. Capillaries
F. Vein
B.
Match the following function of a vessel with its category:
Hydraulic reservoir or Windkessel vessels
A. Arterioles
B. Venule
C. Large arteries
D. Aorta
E. Capillaries
F. Vein
C.
Match the following function of a vessel with its category:
Low resistance conduit
A. Arterioles
B. Venule
C. Large arteries
D. Aorta
E. Capillaries
F. Vein
D.
Match the following function of a vessel with its category:
Exchange vessels
A. Arterioles
B. Venule
C. Large arteries
D. Aorta
E. Capillaries
F. Vein
E.
Match the following function of a vessel with its category:
Determine mean vascular resistance
A. Arterioles
B. Venule
C. Large arteries
D. Aorta
E. Capillaries
F. Vein
A.
The vascular endothelium (true or false):
Is made up of a single layer of endothelial cells and is the surface layer in direct contact with the blood or lymph
True. The endothelium is made up of a single layer of endothelial cells and this surface layer is in direct contact with the blood or lymph.
The vascular endothelium (true or false):
Presents a smooth surface to prevent turbulent flow
True. The endothlium presents a smooth surface to encourage laminar flow.
The vascular endothelium (true or false):
Primarily acts as a non-thrombogenic surface
False. The endothlium does act as a non-thrombogenic surface, however, this is secondary to expressing heparan sulfate, protein C and protein S.
The vascular endothelium (true or false):
Regulates basal vasomotor tone by the controlled release of NO
True. The endothelium regulates basal vasomotor tone by the controlled release of vasodilators, i.e. NO and prostaglandin I2.
The vascular endothelium (true or false):
Regulates blood pressure by consistent release of PAF
False. The endothelium regulates blood pressure by the controlled release of: vasoconstrictors, i.e. endothelins and PAF.
The vascular endothelium (true or false):
Regulates the growth of surrounding connective tissue
F. True. The endothelium regulates the growth of surrounding connective tissue.
The following factor causes alterations in vascular tone (true or false):
Oxygen
True. For most tissues, falling O2 concentration is the strongest stimulus for vasodilation.
The following factor causes alterations in vascular tone (true or false):
Prostacyclin
True. Prostacyclin (PGI2) is formed in the endothelium from arachidonic acid and causes smooth muscle relaxation via increases in cAMAAP.
The following factor causes alterations in vascular tone (true or false):
Haemoglobin
False. Haemoglobin concentration has no effect on the vascular tone.
The following factor causes alterations in vascular tone (true or false):
Potassium
True. H+, K+, H+CO2 and adenosine arise in the tissues and cause vasodilation by direct action on the vascular smooth muscle.
The following factor causes alterations in vascular tone (true or false):
Adrenaline
True. Adrenaline causes vasocontriction through its effects on alpha adrenergic receptors in the vascular smooth muscle of the digestive tract, skin and kidneys. In the skeletal muscle beds, a rich population of β2 adrenergic receptors causes adrenaline mediated vasodilation.
Regarding velocity and turbulence (true or false):
High blood velocity causes flow to be directly proportional to pressure
False. Where the blood velocity is high, a point is reached at which flow is no longer directly proportional to pressure.
Regarding velocity and turbulence (true or false):
Blood velocity is 0.93 cm/s in the ascending aorta and flow is turbulent
True. Flow is turbulent, very briefly, in the early part of the ascending aorta and will only increase in proportion to the square root of pressure.
Regarding velocity and turbulence (true or false):
Turbulent flow occurs at low Reynolds numbers, which tend to produce chaotic eddies, vortices and other flow instabilities
False. Turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce chaotic eddies, vortices and other flow instabilities. Laminar flow is characterized by smooth fluid motion, and occurs at low Reynolds numbers, where viscous forces predominate.
Regarding velocity and turbulence (true or false):
When flow becomes turbulent, the flow rate becomes proportional to the square root of the pressure gradient
True. When flow becomes turbulent, the flow rate becomes proportional to the square root of the pressure gradient, rather than being directly proportional to pressure gradient.
Regarding velocity and turbulence (true or false):
Turbulence increases the energy required to drive blood flow
True. Turbulence increases the energy required to drive blood flow because turbulence increases friction.
Regarding velocity and turbulence (true or false):
The relative roughness of the vessel plays a part in pressure-flow predictions
True. The relative roughness of the vessel plays a part in pressure-flow predictions.
Regarding the relationship between flow, pressure and resistance (true or false):
Flow of any liquid proceeds from a point of higher pressure to one of lower pressure
True. Flow of any liquid proceeds from a point of higher pressure to one of lower pressure.
Regarding the relationship between flow, pressure and resistance (true or false):
Total flow is determined entirely by the length of the vessel and radius of the vessel
False. Total flow is determined by: the pressure gradient, the length of the vessel, the radius of the vessel and the viscosity of the fluid.
Regarding the relationship between flow, pressure and resistance (true or false):
Resistance is the impediment to flow offered by a vessel
True. Resistance is the impediment to flow offered by a vessel.
Regarding the relationship between flow, pressure and resistance (true or false):
Resistance is not affected by whether flow is turbulent or laminar
False. Resistance is determined by whether flow is turbulent or laminar.
Regarding the relationship between flow, pressure and resistance (true or false):
Mathematically, resistance varies directly with viscosity and length, and varies inversely with the fourth power of the radius
True.
Regarding the relationship between flow, pressure and resistance (true or false):
Vessel diameter in the arterioles is the single most important factor in determining mean blood pressure
True
Regarding the effect of viscosity on flow velocity (true or false):
Viscosity is an intrinsic property of fluid that directly affects flow
True. Viscosity is an intrinsic property of fluid related to the internal friction of adjacent fluid layers as they slide past each other.
Regarding the effect of viscosity on flow velocity (true or false):
The formed elements of the blood (red cells, white cells and platelets) increase viscosity
True. The formed elements of the blood (red cells, white cells and platelets) increase viscosity.
Regarding the effect of viscosity on flow velocity (true or false):
Under normal conditions, of all the formed elements of blood, WBC concentration has the greatest effect on blood viscosity
False. Under normal conditions, of all the formed elements of blood, RBC concentration has the greatest effect on blood viscosity.
Regarding the effect of viscosity on flow velocity (true or false):
Blood viscosity increases 2% for each degree centigrade decrease in temperature and leads to changes in systemic haemodynamics and organ flow
True. Viscosity increases 2% for each degree centigrade decrease in temperature. When hypothermia is induced in critical care, it leads to increased blood viscosity and changes in systemic haemodynamics and organ flow.
Regarding the effect of viscosity on flow velocity (true or false):
In arterioles and capillaries, the Lindqvist effect leads to a reduction in the haematocrit relative to larger vessels
E. True. In arterioles and capillaries, the Lindqvist effect leads to a reduction in the haematocrit relative to larger vessels. Cells tend to occupy the central axial stream, effectively reducing the haematocrit. This reduction in viscosity offsets the reduction in velocity in the small vessels.
Regarding the effect of viscosity on flow velocity (true or false):
In the capillaries, blood viscosity is greater than that of plasma
False. In the capillaries, blood viscosity is no greater than that of plasma.
Regarding the effect of viscosity on flow velocity (true or false):
Low flow rates increase the possibility of rouleaux formation and interactions between RBC and plasma proteins
True. Low flow rates increase interactions between RBC (e.g. rouleaux formation) and between RBC and plasma proteins.
Regarding the effect of viscosity on flow velocity (true or false):
Clotting causes a dramatic increase in blood viscosity and associated reduction in blood flow
True. If clotting formation occurs, there is a dramatic increase in blood viscosity and associated reduction in blood flow.
Regarding Starling forces and the capillary network (true or false):
The principle forces governing fluid exchange in the capillary network are hydrostatic pressure and osmosis
False. The principle forces governing fluid exchange in the capillary network are hydrostatic pressure and oncotic pressure.
Regarding Starling forces and the capillary network (true or false):
Starling’s equation describes only the fluid movement due to filtration
True. Starling’s equation describes only the fluid movement due to filtration.
Regarding Starling forces and the capillary network (true or false):
Fluid movement due to filtration is consistent throughout the body
False. Fluid movement due to filtration varies widely throughout the body.
Regarding Starling forces and the capillary network (true or false):
Hydrostatic pressure tends to pull fluid into the plasma
False. Hydrostatic pressure acts to pull fluid into the capillary lumen.
Regarding Starling forces and the capillary network (true or false):
Oedema is the palpable swelling that may occur secondary to a fall in capillary hydrostatic pressure
False. Oedema is the palpable swelling produced by expansion of ISF and may occur secondary to a rise in capillary hydrostatic pressure, a fall in capillary oncotic pressure or increase in capillary permeability.
Concerning the role of the lymphatics (true or false):
The lymphatic system is a primary circulatory system
False. The lymphatic system is a secondary or accessory circulatory system.
Concerning the role of the lymphatics (true or false):
The lymphatic system transports antigen presenting cells
True. The lymphatic system is an important part of the immune system because it transports antigen presenting cells and lymphocytes.
Concerning the role of the lymphatics (true or false):
The lymphatic system removes any excess fluid and proteins that cross into the interstitial fluid
True. The lymphatic system removes any excess fluid and proteins that have crossed from the capillaries into the interstitial fluid.
Concerning the role of the lymphatics (true or false):
The lymphatic system absorbs and transports fatty acids and fats from the digestive tract to the circulatory tree
True. The lymphatic system absorbs and transports fatty acids and fats (as chyle) from the digestive tract to the circulatory tree.
Concerning the role of the lymphatics (true or false):
Lymph nodes filter lymph prior to its return to the systemic circulation
True. Lymph nodes filter lymph prior to its return to the systemic circulation.
Concerning control of circulation through the skin (true or false):
The blood supply to the skin provides modest requirements of nutrient flow that are controlled by local factors
True.
Concerning control of circulation through the skin (true or false):
The blood supply to the skin can provide potentially high flow under reflex control
True. The blood supply to the skin can provide potentially high flow concerned under reflex control when a person experiences heat loss.
Concerning control of circulation through the skin (true or false):
Like the brain, heart and skeletal muscle, the circulation of the skin also exhibits autoregulation where local metabolic influences tend to override neural ones
False. Unlike the brain, heart and skeletal muscle, which exhibit autoregulation where local metabolic influences tend to override neural ones, the circulation of the skin is under powerful sympathetic control.
Concerning control of circulation through the skin (true or false):
The skin contains arteriovenous (AV) anastomoses through which blood may be shunted to the capillaries
False. The skin contains AV anastomoses through which blood may be shunted to the venous plexuses, entirely bypassing the capillaries.
Concerning control of circulation through the skin (true or false):
The AV anastomoses in the skin are controlled by reflex influences from temperature receptors and centres in the anterior hypothalamus
True. These AV anastomoses are controlled by reflex influences from temperature receptors and centres in the anterior hypothalamus, which control heat transfer from the body to the environment via the skin.
